The compounds [Tp(3R,4R,5R)Ir(COD)] (COD = cycloocta-1,5-diene; Tp(3R,4R,5R) = hydrotris(pyrazolyl)borate (1), hydrotris(3-methylpyrazolyl)borate (2), hydrotris(3-isopropylpyrazolyl)borate (3), hydrotris(3,5-dimethylpyrazolyl)borate, hydrotris(3-(trifluoromethyl)-5-methylpyrazolyl)borate, hydrotris(3-phenyl-5-methylpyrazolyl)borate, hydrotris(3,5-diisopropylpyrazolyl)borate, hydrotris(3,4,5-trimethylpyrazolyl)borate, hydrotris(4-chloro-3,5-dimethylpyrazolyl)borate (9), hydrotris(4-bromo-3,5-dimethylpyrazolyl)borate) were prepared and characterized by IR and NMR spectroscopy. The X-ray crystal structure of 9.2MeOH (triclinic, space group P&onemacr; (No. 2); a = 10.044(1) Å, b = 11.186(2) Å, c = 15.499(3) Å; alpha = 77.90(1) degrees, beta = 73.23(1) degrees, gamma = 66.89(1) degrees; Z = 2; R = 0.0276 for 2469 observed reflections) shows that iridium is four-coordinate with an eta(2)-hydrotris(pyrazolyl)borate. The X-ray crystal structure of 1 (triclinic, space group P&onemacr; (No. 2); a = 7.345(1) Å, b = 7.645(1) Å, c = 15.893(5) Å; alpha = 103.17(4) degrees, beta = 90.30(2) degrees, gamma = 93.50(3) degrees; Z = 2; R = 0.0433 for 2606 observed reflections) shows that iridium is five-coordinate with an eta(3)-bonded tris(pyrazolyl)borate. Equilibria between corresponding four- (eta(2)-Tp(3R,4R,5R)) and five-coordinate (eta(3)-Tp(3R,4R,5R)) species of all the complexes are established in solution. The complex containing the ligand HB(Pz(3Me))(3) (Pz = pyrazolyl group) (2) rearranged first to the corresponding complex with HB(Pz(3Me))(2)(Pz(5Me)) and then into that with HB(Pz(3Me))(Pz(5Me))(2). However, 3, which contains HB(Pz(3)()i(Pr))(3), gave only the complex with coordinated HB(Pz(3)()i(Pr))(2)(Pz(5)()i(Pr)).

The optically active pyrazole 4R-methyl-7R-isopropyl-4,5,6,7-tetrahydro-indazole, 3, was prepared from (−)-menthone 1, and used for the preparation of the ligands bis(4R-methyl-7R-isopropyl-4,5,6,7-tetrahydro-N2-indazolyl)methane, 5, bis(4R -methyl-7R-isopropyl-4,5,6,7-tetrahydro-N1,N2-indazolyl)methane, 6, and bis(4R-methyl-7R-isopropyl-4,5,6,7- tetrahydro-N1-indazolyl)methane, 7. Their complexes [Pd(η3-C3H5)(LL)][PF6] (LL = 5, 6 and 7); 9, 10, and 11, respectively, were used as catalyst precursors for the reaction of rac-(E)-1,3-diphenyl-3-acetoxy-l-propene, 12, with dimethylmalonate, 13. When ligand 6 was used methyl 2-carbomethoxy-3,5-diphenyl-4-enoate, 15, was obtained in 84% ee; it was shown that to achieve high ee value it is necessary to have 1 equivalent of chloride ion in the reaction mixture.

The complex [IrH2(eta-3-HBpz*3) (eta-2-COE)] (pz* = 3,5-dimethylpyrazolyl, COE = cis-cyclo-octene) (2) was prepared by hydrogenation of [Ir(HBPZ*3)(COD)](COD = 1,5-cyclo-octadiene) (1) under high pressure ; lower pressures gave a mixture of 2 and [IrH2(eta-3-HBPZ*3)(eta-2-COD)] (3). Protonation of 1 gave [Ir{eta-2-H-theta(pz*2) (Hpz*2 (COD)] [CF3SO3] (Hpz* = protonated 3,5-dimethylpyrazolyl) (4). The complexes [Ir(HBpz'3) (COD)] (5) (pz' = 3,4,5-trimethylpyrazolyl), [Ir(HBpz*3) (C2H4)2] (7) and their corresponding dihydride complexes, [IrH2(eta-3-HBpz'3) (COE)] (6) and [lrH2(eta-3-HBpz*3) (C2H4)] (8), are also described. Complex 2 is very stable and unreactive and its structure was determined by NMR and X-ray diffraction studies. Crystal data for [IrH2(eta-3-HBpz*3) (eta-2-COE)]: C23H38N6Blr; a = 31.041(7), b = 8.233(1), c = 22.475(4) angstrom, beta = 118.082-degrees, monoclinic, space group C2/c, (No. 15), Z = 8, final R(W) factor 0.0622 for 2023 observed reflections, having I greater-than-or-equal-to 4-sigma(I). The structure of 2 is remarkable in that the C=C of the COE roughly bisects the H-Ir-H angle. This unusual alkene orientation is analyzed via extended Huckel calculations using a structure based on the crystal structure of 2. It is shown that this conformation permits optimal back-bonding from the d-block into the alkene pi-*cc. It is shown that the orientation of alkenes coordinated to d6 ML5 fragments is highly sensitive to the detailed geometry of the spectator ligands around the metal. The orientation of H-2 in the place of alkene in 2 is also examined.